The invention pertains to cargo transportion vehicles or equipment such as conventional vans and insulated type vans for heavy trucks, semi-trailers and the like and in particular to the hardware used with the side doors of such equipment. In order to maximize their operational efficiency, the inside width of such vans is made as large as feasible and inasmuch as the overall outside width of the vehicle is limited by regulations, the thicknesses of the side walls consequently is of importance. Thus, where a door is installed into a side wall, the thickness of the door itself as well as the spatial requirements of the hardware for hinging and locking the door requires special design considerations in order to avoid the otherwise unnecessary thickening of the side wall or encroachment, in widthwise direction, on the overall outside width.
The thickness of a side door of a van of the type used for the transportation of general cargo is determined primarily by the operational forces exerted against the door itself. The thickness must be adequate to contain the cargo safely, barring a catastrophic road accident. In the case of insulated vans, the thickness of its several walls are determined primarily by the degree of insulation required for the intended service. The presence of a side door requires that its installation does not appreciably reduce the thermal efficiency of the side wall including its door, in the case of an insulated vehicle and in any event, the hardware must not require so much space for mounting an installation as will cause it to protrude excessively or as will require modification of the van structure either to encroach upon the otherwise useful cargo space or detrimentally affect either the structural or insulating integrity of the vehicle.
The hinging of a side door requires the hardware not only to have a minimal spatial requirement but also from a practical operational viewpoint to permit the door to be swung open approximately 180.degree. to lie as flat as possible against the adjacent side wall.
The requirement that a side door be hinged to allow approximate 180.degree. swing is commonly achieved by locating the vertical hinge line of a conventional single pivot hinge to be as close as possible to the outside surface of the van body. Additionally, the strap portion of the hinge which is secured to the door is angled inboard from the hinge line and secured to the outside surface of the door which is set well inboard of the van body surface, thereby decreasing the thickness of the door.
The locking hardware, as commonly used, comprises a vertical lock rod located on the outer surface of the door adjacent its free swinging edge and journalled to rotate about its vertical axis. Upon rotation of the locking rod, locking fingers attached at the ends thereto engage with frame-mounted keepers, and further rotation of the rod causes the door to be forced into its closed position. Such hardware, as in the case of the hinging hardware, is designed and installed so as not to protrude beyond the outside surface of the van body. This requires that the outside surface of the door, or as a minimum that portion of the door on which the hardware is installed, to be inset from the van body surface. Therefore, with such prior art hinging and locking hardware, the overall door thickness is undesirably yet necessarily reduced or, alternatively, if a given door thickness is required, the door in its entirety must be set further inboard and this, of course, then reduces the cargo cubage of the van.
Although double pivot hinges have been contemplated in the prior art, as is evidenced by U.S. Pat. Nos. 1,988,585 and 2,071,236, separate hinging and latching or keeper mechanism is provided therein.